Presser device for sewing machines



April 24, 1951 H. RITTER I A PRESSER-DEVICI: FOR SEWING MACHINES Filed Jan. 7, 1949 Patented Apr. 24, 195i UNITED STATE ENT OFFICE Singer Manufacturing Company, Elizabeth,

N. J., a corporation of New Jersey Application January 7, 1949, Serial No. 69,675

6 Claims.

This invention relates to sewing machines, and is principally concerned with an improved form of presser device for opposing the usual feed-dog in advancing the work past the stitch-forming instrumentalities of the sewing machine. The presfact that the vertically yielding presser-foot fails to follow closely the work-feeding portions of the descending movements of the feed-dog above the level of the usual throat plate. This results in a lessening of the feeding pressure exerted by the resser-foot with the attendant reduction in the efilciency of feeding. One of the causes of the failure of the presser-foot to follow closely the descending movements of the feed-dog is the upward momentum of the presser-foot and presserbar at the top of the feed-dog rise. Another cause is the cramping of the presser-bar in its bearings resulting from the sidewise thrust imposed on the presser-bar by the feed-dog in its advance of the work.

In an effort to eliminate the two above described causes of defective feeding, I have devised a presser-foot constructed so that a minimum of weight is shifted in response to the ascent and descent of the feed-dog. Also, the yieldable member carrying the presser-foot sole-plate. is shifted in response to the movable feed-dog in a direction inclined to the normal direction of feed, the spring which. biases the yieldable member being disposed to operate axially of said member. The movable parts of the press'er-device being of very light-construction and substantially devoid of any material cramping action, a very light spring is effective in holding the presser-foot against the work at high speeds of operation of the machine.

Other features and advantages of the invention will appear from the following description of a preferred embodiment shown in the accompanying drawing, in which:

Fig. 1 is an end elevation, with the throat-plate in section, of a portion of a sewing machine equipped with the present invention.

Fig. 2 is an enlarged right side elevation, partly in section, of the presser-device and the asso ciated parts of the sewing machine, showing the feed-dog in its raised or effective feeding position.

Fig. 3 is a' right side elevation, further enlarged, of the lower portion of the presser-device of which the supporting body thereof is sectioned to illustrate the pivoted support for the tilting presserfoot or sole-plate which is shown, in full lines, in its depressed position and, in dotted lines, in its fully elevated position.

Fig. 4 is an enlarged section taken substantially along the line 44, Fig. 1.

In the drawing, the sewing machine illustrated is a conventional lock-stitch machine having a frame including a bed E0 and an overhanging head l1. Journaled for endwise reciprocation in the head I l is a needle-bar l2 carrying at its lower end a thread-carrying needle l3. Journaled in the bed H! is a rotary hook it complemental to the needle [3 in producing lock-stitches in the work W which is supported at the stitching. zone by the usual throat-plate A5. The work W is ad vanced past the stitch-forming devices by a conventional feed-dog l6 secured on a feed-bar ll connected at one end to a feed-advance and -return rocker i8 and at its other end to a feed-lift rock-arm E9. The feed-advance and -return rocker I8 and the feed-lift rock-arm I9 are adapted to be actuated in the usual manner to impart advance-and-return and rising-and-falling movements to the feed-dog l6, Wherebyit traverses the usual four-motion path.

Opposed to the feed-dog i6 is my improved Dresser-device carried on the lower end of a spring-depressed presser-bar 2!] endwise slidable in the machine-head H. The spring for forcing the presser-bar 20 downwardly, although not shown in the accompanying drawing, is a relatively stiff spring and is preferably mounted as shown in my previously mentioned Patent No. 2,344,414.

In its preferred form, the presser-device comprises a body-member 21 provided with a socket 22 into which is adapted to project the lower end of the presser-bar 20, a screw 23 threaded into the presser-bar serving to clamp the presserdevice on the presser-bar. Formed in the bodymember 2! of the presser-device is a bore 24 upwardly inclined to the plane of the throat-plate l5 in the direction of feed. Slidably disposed in the lower portion of the bore 2 5 is a cylindrical block 25 fitted with a transverse pivot-pin 26 on the opposite ends of which is pivoted the spaced upstanding side-plates 21, 28 of a presser-foot 29. To provide for limited endwise movement of the cylindrical block 25, in response to the rising and falling movements of the feed-dog and the usual variations in the thickness of the work W, the transverse hole in the body-member 2! through which the pivot-pin 26 projects is elongated in a direction parallel to the axis of the bore 24 to provide a slot 30. The presser-foot 29 is biased downwardly relative to the body-member 2| by means of a coil-spring 31 which is disposed in the bore 24. The pressure exerted by the coil-spring against the cylindrical block 25 is adapted to be controlled by an adjusting screw 32 fitted with a lock-nut 33.

In practice, the presser-bar 20 is depressed into a fixed lowered position determined by the usual presser-bar hand lever in the manner shown and described in my above mentioned U. S. Patent No. 2,344,414, and the presser-bar spring is strong enough to hold the presser-bar 20 in its lowest position during the feeding operation of the machine. The coil-spring 3| is made considerably lighter or of smaller scale than the presser-bar spring and, during sewing, the coil-spring 3! yields to permit displacement of the presser-foot 29 relative to the presser-bar 2B in response to the rising and falling movements of the feed-dog 16. It will be appreciated that the displacement of the presser-foot 29 is along the axis of the bore 24 in the body-member 2i and that the only parts which move are the presser-foot 29, the cylindrical block 25 and the lower end portion of the coil-spring 3!. Obviously, by moving only these few parts, which are of small size and weight, the forces of inertia are maintained at a minimum. Also, by constraining the cylindrical block 25 to move along the axis of the bore 24, the presser-foot 29 moves upwardly in the direction of feed-dog thrust, thereby obviating the usual vided with an upwardly inclined bore, a block slidably disposed in said bore, a presser-foot pivotally mounted on said block, the pivotal-axis of said presser-foot intersecting said bore, and a spring acting in a direction axially of said bore for depressing said presser-foot.

2. A presser-device for sewing machines having a presser-bar, comprising a body-member adapted to be secured to said presser-bar and having an upwardly inclined bore, a blockslidably disposed in said bore, a presser-foot, a pivotal support for said presser-foot extending from said block and disposed to intersect said bore, and a spring disposed in said bore and operatively associated with said block for depressing aid oresser-foot.

3. A presser-device for sewing machines having a presser-bar, comprising a body-member adapted to be secured to said presser-bar and having an upwardly inclined bore, a block slidably disposed in said bore, a pivot-pin carried by said block and disposed to intersect said bore transversely, a presser-foot hinged on said pivotpin, and a spring located in said bore and engaging said block for depressing said presser-foot.

4. A presser-device for sewing machines having a presser-bar, comprising a body-member having an upwardly inclined bore and a transverse slot, a block slidably disposed in said bore, a pivot-pin carried by said block and extending through said transverse slot in said body-member, a presser-foot hinged on said pivot-pin, and a spring located in said bore and engaging said block for depressing said presser-foot.

5. A detachable presser-unit for sewing machines having a presser-bar, comprising a bodymember adapted to be attached to said presserbar and having a mutually perpendicular bore and slot formed therein, a block slidably disposed in said bore, a pivot pin carried by said block perpendicular to the axis of said bore and extending through said slot in the body member to confine the block for limited translation in said bore, a presser-foot carried by said pivotpin, a spring acting axialiy of said bore for biasing said presser- ,ioot downwardly, and means for controlling the pressure exerted by said spring.

6. A detachable presser-unit for sewing machines having a presser-bar, comprising a bodymember adapted to be attached to said presserbar and having a mutually perpendicular bore and slot formed therein, a block slidably disposed in said bore, a pivot pin carried by said block perpendicular to the axis of said bore and extending through said slot in the body member to confine the block for limited translation in said bore, a presser-foot carried by said pivot-pin, a spring disposed in said bore and. bearing at one end against said block, and a spring-pressure adjusting screw contacting the other end of said spring.

HERMAN BITTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

